<!DOCTYPE html>
<html>
<head>
	<title></title>
	<script type="text/javascript">
		
		var sum=0;//成绩总和
		for(var i=1;i<=5;i++){//循环五次，到六结束，五次相加和除5
			var num=Number(prompt('输入'+'第'+i+'门课成绩'));//输入五门课成绩
			sum +=num;
		}
		console.log(sum/5);
	</script>
</head>
<body>

</body>
</html>